Safety improvements for airport runways and taxiways

ABSTRACT

Safety improvements of airport runways and taxiways are achieved by providing a flexible, water-impermeable surfacing material on a compacted soil base directly adjacent to an edge of airstrip shoulders. A synthetic grass surface is provided on the area beyond the surfacing material so that foreign objects such as loose particles of the airstrip shoulder materials will be driven by jet blasts and run-off across the relatively smooth texture of the surfacing material and will be trapped by the synthetic grass, thereby minimizing foreign object damage to aircraft engines, particularly to those overhanging engines which extend well beyond the existing runway and taxiway shoulders.

FIELD OF THE INVENTION

[0001] The present invention relates to safety improvements for airporttaxiways and runways and particularly to the need to increase the widthof taxiways and runways at airports in order to minimize the risk offoreign object damage to aircraft engines, as well as the safety issuesregarding the deterioration of the existing natural grass surfacesbounding taxiways and runways.

BACKGROUND OF THE INVENTION

[0002] With the advent of larger and more powerful planes circulating onairport runways and taxiways that were constructed many years ago, thereis a serious safety concern regarding overhanging engines which nowfrequently extend well beyond the existing runway and taxiway shoulders.The new generation of aircraft presently being manufactured have verylarge wing spans resulting in the jet engines overlapping the existingrunway and taxiway shoulders, and in many cases actually hanging overthe natural grass areas bounding the runway or taxiway, thus greatlyincreasing the risk of damage to aircraft engines by the presence offoreign objects.

[0003] The majority of airport runway and taxiway shoulders areconstructed of asphalt which may have deteriorated surfaces and edges,such as cracking and spalling. This creates a serious risk of damage toaircraft and particularly aircraft engines overhanging the airstripshoulders caused by foreign objects such as loose pieces of asphalt anddebris that could be ingested by the aircraft engines. Foreign objectdamage is a primary safety concern for both airport operators andaircraft manufacturers since it could have catastrophic results. Inaddition to foreign object damage potential, asphalt pavements requireperiodic maintenance and/or complete replacement which adds to theoverall airport operation costs.

[0004] In order to minimize the risk of foreign object damage toaircraft engines and in order to comply with regulatory safety issues,one solution is to increase the width of existing runways and taxiwaysusing concrete or asphalt placed over deep bases in traditionalconstruction methods. However, the costs related to traditionalconstruction methods and to airport operation down-time resulting fromthe traditional construction are very significant and in some cases notfeasible.

[0005] Air fields are generally constructed in large open areas and soin addition to jet blasts and vortex shedding, they are exposed to windstorms, ice and snow storms as well as sand storms, which requiresexpensive maintenance of existing topsoil bounding the runways andtaxiways, such as cutting, grooming, cleaning, etc., in order to ensureefficient surface drainage of water, and to avoid water ponding andpossibly freezing of the surface water on the runway.

[0006] Therefore, there is a need for improvement of airport runways andtaxiways, particularly the need for improvements of the extension ofexisting runway and taxiway shoulders.

SUMMARY OF THE INVENTION

[0007] An object of the present invention is to provide a method forimproving safety of airport runways and taxiways.

[0008] Another object of the present invention is to provide acost-effective solution for the extension of existing runway and taxiwayshoulders at airports in order to minimize the risk of foreign objectdamage to aircraft engines.

[0009] A further object of the present invention is to provide anairport runway and taxiway shoulder-bordering surface arrangement toextend the width of existing runway and taxiway shoulders, therebyreducing the potential for damage to aircraft engines by foreignobjects.

[0010] In accordance with a general aspect of the present invention,there is provided a method for improving safety of airport airstripscomprising steps of:

[0011] a) providing a flexible surfacing material; and

[0012] b) extending the width of an existing shoulder of the airstrip byinstalling said flexible surfacing material along a side of saidairstrip.

[0013] In accordance with a more specific aspect of the presentinvention, the method comprises the steps of: providing a compacted soilbase bounding a shoulder of an airstrip; placing a flexible,water-impermeable surfacing material on the compacted soil base; andanchoring the surfacing material to the airstrip in a water-tight mannerso that the surfacing material will assure efficient surface drainage ofwater and allow for unobstructed run-off of loose particles.

[0014] It is preferable to further lay a synthetic grass surface on anarea beyond the surfacing material so that loose particles can betrapped thereby when being driven by jet blasts from the airstrip andrunning off the surfacing material.

[0015] In accordance with another aspect of the present invention, anairport runway and taxiway shoulder-bordering surface arrangement isprovided to extend the width of existing runway and taxiway shoulders,thereby eliminating the potential for damage to aircraft engines byloose particles. The arrangement comprises a compacted soil basebounding an airstrip and a flexible water-impermeable surfacing materialplaced on the compacted soil base and directly adjacent to a side edgeof the airstrip. Means are provided for anchoring the surfacing materialto the edge of the airstrip in a water-tight manner so that thesurfacing material will assure efficient surface drainage of water andallow for unobstructed run-off of loose particles. It is noted that theflexible water-proof surfacing material can be installed directly on theexisting paved airstrip shoulder area in order to reduce the cost ofexcavating the existing asphalt and to keep the existing shoulder inplace.

[0016] In accordance with a further general aspect of the presentinvention, there is provided an airfield safety arrangement for reducingthe risk that an aircraft engine be damaged as a result of the ingestionof foreign objects from an area adjacent an airstrip, the safetyarrangement comprising a ground surfacing material adapted to be laiddown on the ground so as to extend laterally outwardly from an airstrip,the ground surfacing material having a relatively smooth sheddingsurface sloping downwardly from the airstrip to provide for surfacewater drainage and run-off of loose particles to a location wherein theparticles are not subject of being ingested by the engines of theaircrafts on the airstrip, and an edge anchoring system for bonding theground surfacing material in a water-tight manner to the airstrip. Thesurfacing material may be provided with a textured pattern as long as itdoes not impede run-off of loose particles.

[0017] Still in accordance with the present invention, there is providedan airstrip shoulder-bordering surface arrangement for extending thewidth of existing runway and taxiway shoulders in order to reduce thepotential for damage to aircraft engines by foreign objects (FOD), thearrangement comprising a flexible water-impermeable surfacing materialadapted to extend laterally of a side edge of an airstrip shoulder; andan edge-fastening system for securing the surfacing material in positionrelative to the airstrip shoulder and prevent water migrationtherebetween, the surfacing material having a relatively smooth topsurface to provide for water surface drainage and unobstructed run-offof loose particles.

[0018] The surfacing material preferably further includes reflective andluminescent materials (for instance phosphorescent materials) to provideperimeter lines and runway identification markings so that in situationswhere the luminescent effect of the reflective materials has faded theaircraft lights would be reflected. The reflective or luminescentmaterials can be provided as an integral part of the surfacing materialor can be applied thereon such as by bonding, painting or other by usingany other appropriate techniques. The surfacing material is preferablyin a green colour, or could be other colours if required to make astrong visual contrast between the runway and taxiway edges and the edgeof the natural field.

[0019] In another embodiment of the present invention, the arrangementfurther includes a synthetic grass surface covering an area beyond thesurfacing material which is permanently bonded to the surfacingmaterial. Thus, the relatively smooth texture of the surfacing materialwill allow for unobstructed run-off of any loose particles that might bepresent on the runway and taxiway shoulders and could present apotential for foreign object damage to aircraft engines. As an addedvalue, the replacement of natural grass surfaces with the surfacingmaterial in combination with the synthetic grass surface can provideconsiderable cost benefits with regards to airport maintenance budgets.This artificial grass can be either permeable or impermeable dependingon the specifications for the specific application.

[0020] Substantial savings in airport maintenance budgets can beachieved with the installation of the surfacing material which isvirtually maintenance free. In addition, the installation of thesynthetic grass surface would eliminate the need for the trimming andcutting of natural grasses. The artificial grass would retain itspermanent green colour and texture throughout the year, thus eliminatingthe need to re-sod old and dead natural grass. In hot and arid climates,for example, in the Middle East, the relatively smooth shedding surfaceof the surfacing material would allow the removal of sand and otherloose foreign objects quickly and efficiently from the shoulders simplyas a result of the wind or air turbulence created by aircrafts or othermechanical means. Regular maintenance to keep the extended shouldersfree of hazardous debris can be conducted easily, quickly andeconomically. The debris is displaced into the adjacent synthetic grassturf where the debris will be trapped. If necessary the accumulateddebris can be vacuumed out periodically.

[0021] In cold climates accumulated snow can be easily and quicklyremoved from the surfacing material either by large blowers or sweepers,to a distance beyond the overhang of aircraft engines.

[0022] Since the surfacing material is completely water-tight, the riskof settlement and deterioration of the supporting base would beeliminated, thus providing a stable base for maintenance vehiclecirculation year-round.

[0023] The pattern of installation of the surfacing material with theseams running parallel to the existing shoulder edges would notinterfere with maintenance operations.

[0024] Other advantages and features of the present invention will bebetter understood with reference to preferred embodiments thereofdescribed hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Having thus generally described the nature of the invention,reference will now be made to the accompanying drawings, showing by wayof illustration a preferred embodiment thereof, and in which:

[0026]FIG. 1 is a perspective view of an airport runway having shoulderextensions in accordance with a preferred embodiment of the presentinvention;

[0027]FIG. 2 is a cross-sectional view of an airstrip shoulder-borderingarrangement in accordance with a first embodiment of the presentinvention; and

[0028]FIG. 3 is a cross-sectional view of an airstrip shoulder-borderingarrangement in accordance with a second embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0029]FIG. 1 illustrates an airport runway 10 comprising a centraltake-off/landing strip 11 and a pair of runway shoulders 12. Eachshoulder 12 is extended laterally outwardly by means of ashoulder-bordering arrangement comprising a soft ground cover orflexible water-proof surfacing material 14.

[0030] As shown in FIG. 2, the installation of the surfacing material 14normally begins with a first step of removing the existing organicmaterial contained in the uppermost stratum of the ground G bounding theshoulders 12 of the runway or taxiway which is generally referred to asan airstrip throughout this application, to a depth dictated by the soilreport. The ground G is excavated down to a compactable earth surface.At that point, the soil is graded and compacted by being rolled andshaped to meet the required slopes such that the flow of surface waterwill be controlled to drain to specific locations. The rocks are removedfrom the compacted soil base and if required, a layer of engineeredbackfill will be installed and compacted prior to installing thesurfacing material 14 directly on the compacted backfill if specified todo so. It is noted that in some applications, the surfacing material 14may be laid down directly on the ground without the need for excavating.

[0031] The flexible surfacing material 14, which is a plastic composite,for example polypropylene, urethane, vinyl or polyethylene, is laiddirectly on the compacted soil base adjacent to the edge of the existingairstrip shoulder 12. As shown in FIG. 3, the surfacing material 14 mayalso be installed so as to at least partly cover or overlap the shoulder12 of the airstrip (i.e. the runway or the taxiway). This isparticularly applicable in the case where the existing shoulder wouldhave to be repaired or re-paved. The surfacing material 14 has arelatively smooth texture having a thickness of between 50 mm and 400mm. The surfacing material 14 can be provided in the form of apolyethylene, polypropylene or any other type of plastic or compositematerial that can be sprayed or laminated upon a mesh substrate. Thepolyethylene or any equivalent thereof could be sprayed or applied byvarious methods on site or at the manufacturing plant. The surfacingmaterial 14 is completely water-impermeable and is preferablypermanently bonded to an edge-fastening system or anchoring system 16placed next to the existing airstrip shoulder edges or to the shoulder12 directly since all installations are different.

[0032] The installation of the surfacing material 14 is completed byoverlapping rolls of the surfacing material and applying a heattreatment, such as thermal welding, or by applying adhesives to theoverlapping surfacing materials, thus fusing the two materials togetherto obtain a permanent, water-tight and strong bonding of the seams.

[0033] In the illustrated embodiment, the surfacing material 14 isbonded in a water-tight manner to the airstrip shoulder 12. Moreparticularly, the interface between the edge of the existing airstripshoulders and the first roll of the surfacing material can be madewater-tight by installing impermeable elastomeric sealers in order toassure a continuous and uninterrupted surface drainage of theimpermeable surface. The impermeable elastomeric sealer is incorporatedwith the specially designed anchoring system 16 which assures the safe,permanent and economical anchoring of the edges of the surfacingmaterial 14 to the immediately adjacent existing airstrip shoulders 12.

[0034] The anchoring system 16 preferably includes a prefabricated,extruded plastic member 18, for example polypropylene or other plasticthat can be thermally bonded to the flexible surfacing material 14. Theextruded plastic member 18 is partially embedded in specially formulatedexpanding foam 20 which is injected into a narrow excavated trench alongthe edge of the airstrip shoulder 12. The excavation, injection of foam,and bonding of the plastic member 18 are completed simultaneously in oneoperation. The plastic member 18 has an anchoring portion 24 from whichextends a leg 26 supporting an above-ground section or head 22 to whichthe first row of surfacing material 14 is thermally or mechanicallybonded. For instance, bonding of the surfacing material 14 can be doneby applying a heat activated treatment or by applying adhesives to theoverlapping of the surfacing material 14 and the extruded plastic member18, thus permanently fusing the two materials together. This anchoringsystem 16 provides a water-tight seal between the airstrip shoulder edgeand the surfacing material 14. A sealer 27 is preferably provided alongthe vertical interface between the shoulder 12 and the ground surfacingarrangement, as shown in FIG. 2.

[0035] When the entire surfacing material 14 is in place, the surfacingmaterial 14 will take the shape and the slope of the underlyingcompacted soil base and will stay flat to provide the relatively smoothshedding surface to provide for water drainage and run off of looseparticles. The extent in width and length to which the surfacingmaterial 14 is installed will depend on the performance and designcriteria of the specific sites. The areas beyond the surfacing material14 could be covered with artificial grass 30 which would trap any bornparticles, such as sand displace by aircraft. The synthetic grasssurface is permanently bonded to the surfacing material 14 such as byapplying the thermal welding technique or by applying adhesives toassure a permanent water-tight seam between the surfacing material 14and the synthetic grass surface 30.

[0036] The synthetic grass surface 30 generally includes a pile fabric32 which is preferably placed over a compacted soil base substantiallyfree of organic matter. The pile fabric 32 includes a plurality of pileelements 34 resembling blades of grass and extending from a relativelythin and flexible backing mat 36 to a predetermined height thereabove. Anon-water retaining ballast material 38 for stabilizing the pile fabric32 in place is provided on the backing mat 36 and has a thickness lessthan the predetermined height of the pile elements 34. The ballastmaterial 38 is provided in the form of a relatively thick layer ofparticulate material dispersed among the pile elements 34 on the backingmat 36. The synthetic grass is typically installed on a sloped base fordirecting water from the pile fabric 32 to the designed storm watermanagement system. Surface drainage is important since it is easier toprepare and can work at lower cost.

[0037] The rows of pile elements 34 can be similar to that described inApplicant's co-pending Canadian Patent 2,218,314 filed on Oct. 16, 1997,and laid open on Sep. 10, 1998, the contents of which are incorporatedherein by reference.

[0038] A thin impermeable membrane 40 is laid on the compacted soil baseto prevent water from percolating down thereto. A drainage enablinglayer 42 which comprises a thick layer of aggregate, such as rockparticulates, is provided on the impermeable membrane 40. The flexiblebaking mat 36 is placed on the drainage enabling layer 42 so that thewater can readily flow from the backing mat 36 through the drainageenabling layer 42 onto the impermeable membrane 40 and into storm sewersplaced at strategic locations. This embodiment is described with moredetails in Applicant's PCT application PCT/CA01/01275, entitledARTIFICIAL GRASS FOR LANDSCAPING, filed Sep. 5, 2001, the specificationsof which is incorporated herein by reference. It is noted that the waterbarrier could be integrated to the backing mat 36 in which case theinfill layer 38 would act as the drainage enabling layer.

[0039] As shown in FIG. 2, the surfacing material 14 can be bonded tothe edge of the impermeable membrane 40 to provide a water-tight sealbetween the synthetic grass surface 30 and the surfacing material 14.Alternatively, the surfacing material could be placed underneath thebacking mat 36 and be thermally or adhesively bonded thereto.

[0040] As an added safety feature, the surfacing material 14 can befabricated with a permanent colour such as green, or with other coloursif required to enhance visual contrast between the central landing zoneof the airstrip 10 and the shoulders 12 thereof. The surfacing material14 can also be designed to accept solar energy absorbing fabrics whichwill dissipate a luminescent glow during the night without the need ofoutside power sources. The luminescent reflective glow would last up to10-12 hours to cover the dusk to dawn period. The solar absorbing fabriccan be coated directly onto the installed surfacing material 14 or canbe installed during fabrication. Patterns spacing and shape factors canbe custom fabricated to meet specific airport operation specifications.The solar absorbing fabric can advantageously replace conventionallighting systems for small airports.

[0041] The surfacing material 14 can further include special reflectivefabrics installed thereon to enhance the visibility of the runway pathfor aircraft landing during the night. Thus in situations where theluminescent effect of the solar absorbing fabric fades, the aircraftlights will be reflected by the one-way reflective fabrics to facilitatesafe landing.

[0042] As shown in FIG. 3, the surfacing material 14 can be installeddirectly on an existing shoulder 12 and anchored thereto by means of ananchor member 18′ provided in the form of a plastic extrusion placed ina trench formed in the shoulder 12 and fixed in position therein bymeans of a plurality of anchoring bars. The surfacing material 14 can bethermally or adhesively bonded to the anchor member 18′ or evenmechanically attached thereto, as described hereinbefore with respect toFIG. 2. Alternatively, the surfacing material 14 could be adhesivelybonded directly to the shoulder 12. A given thickness of material isremoved from the shoulders 12 so that the surfacing material 14 issubstantially flush with the take-off/landing strip 11.

[0043] Protection against foreign object damage (FOD) can be furtherenhanced by incorporating a guidance system into the surfacing materialfor guiding a robot 48 parallel the runway 10 in order to locate anddetect FOD materials that could be ingested by the aircraft engines. Theguidance system could include a magnetic guidance wire 46 embedded inthe surfacing material 14 or any other type of guidance technology.

[0044] By having guidance wires embedded into the flexible surfacingmaterial 14, drainage of the runway would not be impeded by channels orprotruding edges to guide the robots 48. The robots 48 could also bedesigned to clear the flexible fabric of sand and FOD by means of havinga larger robot made with the necessary blowers to do so. The FODdetecting robot would need to be heavy and stable enough to not bedisplaced from the wind and or jet wash. A cable system could also beused to guide the robot along and keep the robot tethered.

[0045] Modifications and improvements to the above-described embodimentof the present invention may become apparent to those skilled in theart. The foregoing description is intended to be exemplary rather thanlimiting. The scope of the invention is therefore intended to be limitedsolely by the scope of the appended claims.

What is claimed is:
 1. A method for improving safety of airportairstrips comprising the steps of: a) providing a flexible surfacingmaterial having a relatively smooth surface; and b) extending the widthof an existing shoulder of the airstrip by laying down said flexiblesurfacing material along a side of said airstrip with said smoothsurface providing for unobstructed run-off of loose particles from theairstrip.
 2. A method as defined in claim 1, wherein said surfacingmaterial is water-impermeable and wherein step b) comprises the step ofproviding a relatively smooth transition between the surfacing materialand the airstrip to provide for surface drainage of water andunobstructed run-off of loose particles.
 3. A method as defined in claim2, wherein step b) further comprises the steps of: anchoring thesurfacing material in position with said surfacing material extendinglaterally beyond the shoulder of the airstrip, and providing awater-tight seal between the airstrip and the surfacing material.
 4. Amethod as defined in claim 3, wherein said surfacing material at leastpartly covers the shoulder of the airstrip.
 5. A method as defined inclaim 3, wherein said surfacing material extends laterally outwardlyfrom the shoulder of the airstrip.
 6. A method as defined in claim 3,wherein the step of anchoring the surfacing material includes the stepof installing an anchor, and securing the surfacing material to saidanchor.
 7. A method as defined in claim 6, wherein said surfacingmaterial is heat welded to said anchor.
 8. A method as defined in claim7, further comprising the step of providing a sealer at an interfacebetween said surfacing material and the airstrip.
 9. A method as definedin claim 1, wherein step a) comprises the step of laying down thesurfacing material on a pre-compacted soil base bounding the shoulder ofthe airstrip.
 10. A method as defined in claim 1, wherein step a)includes the step of laying down the surfacing material on a surfacesloping downwardly from the shoulder of the airstrip.
 11. A method asdefined in claim 9, comprising the step of incorporating a guidancesystem to said surfacing material, and using said guidance system tooperate a robot along the airstrip to detect the presence of FODmaterials.
 12. A method as defined in claim 1, further comprising thestep of providing airstrip markings on said surfacing material forguiding pilots along the airstrip during airplane taking-off and landingoperations.
 13. A method as defined in claim 12, wherein the step ofproviding airstrip markings on said surfacing material comprises thestep of bonding at least one of a reflective material and a luminescentmaterial to said surfacing material.
 14. A method as defined in claim 1,further comprising the step of laying a synthetic grass surface on anarea beyond the surfacing material so that loose particles can betrapped thereby when being driven by jet blasts from the airstrip andwhen running off the surfacing material.
 15. A method as defined inclaim 14, further comprising the step of heat sealing an edge of saidsynthetic grass surface to said surfacing material.
 16. An airstripshoulder-bordering surface arrangement for extending the width ofexisting runway and taxiway shoulders in order to reduce the potentialfor damage to aircraft engines by foreign objects (FOD), the arrangementcomprising a flexible water-impermeable surfacing material adapted toextend laterally of a side edge of an airstrip shoulder, and anedge-fastening system for securing the surfacing material in positionrelative to the airstrip shoulder and prevent water migrationtherebetween, the surfacing material having a relatively smooth topsurface to provide for water surface drainage and unobstructed run-offof loose particles.
 17. An airstrip shoulder-bordering surfacearrangement as defined in claim 16, wherein said flexiblewater-impermeable surfacing material slopes from the edge of theairstrip shoulder to an area covered with artificial grass adapted totrap the loose particles running-off the surfacing material.
 18. Anairstrip shoulder-bordering surface arrangement as defined in claim 17,wherein a water-tight joint is provided between the artificial grass andthe surfacing material.
 19. An airstrip shoulder-bordering surfacearrangement as defined in claim 17, wherein said artificial grass isheat bonded to said surfacing material.
 20. An airstripshoulder-bordering surface arrangement as defined in claim 16, whereinsaid surfacing material is made of a plastic composite material.
 21. Anairstrip shoulder-bordering surface arrangement as defined in claim 20,wherein said plastic composite material is selected from a groupconsisting of: polypropylene, urethane, vinyl and polyethylene.
 22. Anairstrip shoulder-bordering surface arrangement as defined in claim 16,wherein said surfacing material is laid on a layer of compactedengineered base material.
 23. An airstrip shoulder-bordering surfacearrangement as defined in claim 16, wherein said edge-fastening systemincludes an anchor partly buried in the soil along the side edge of theairstrip shoulder, said anchor having a head bonded to a longitudinalside edge of said surfacing material.
 24. An airstrip shoulder-borderingsurface arrangement as defined in claim 23, wherein said anchor isprovided in the form of an extrusion having a bottom anchoring portionconnected to said head via an upstanding leg portion.
 25. An airstripshoulder-bordering surface arrangement as defined in claim 24, whereinsaid above-ground portion is thermally fused to said longitudinal sideedge of said surfacing material.
 26. An airstrip shoulder-borderingsurface arrangement as defined in claim 23, wherein said anchor ispartly embedded in expansion foam.
 27. An airstrip shoulder-borderingsurface arrangement as defined in claim 16, wherein airstrip markingsare provided on said surfacing material, said airstrip markings beingmade of at least one of a reflective material and a luminescentmaterial.
 28. An airstrip shoulder-bordering surface arrangement asdefined in claim 27, wherein said surfacing material is of a differentcolor than the airstrip in order to enhance visual contrast between theairstrip and the shoulders thereof.
 29. An airstrip shoulder-borderingsurface arrangement as defined in claim 16, wherein a guidance system isincorporated to said surfacing material to guide a robot along theairstrip in order to locate and detect FOD materials susceptible ofbeing ingested by an aircraft engine.
 30. An airfield safety arrangementfor reducing the risk that an aircraft engine be damaged as a result ofthe ingestion of foreign objects from an area adjacent an airstrip, thesafety arrangement comprising a ground surfacing material adapted to belaid down on the ground so as to extend laterally outwardly from anairstrip, the ground surfacing material having a relatively smoothshedding surface sloping downwardly from the airstrip to provide forsurface water drainage and run-off of loose particles to a locationwherein the particles are not subject of being ingested by the enginesof the aircrafts on the airstrip, and an edge fastening system forbonding the ground surfacing material in a water-tight manner to theairstrip.